The present invention relates to the field of sanitizing pools and spas. In particular, the present invention relates to an automated system for adding an electrolytic solution (i.e. sodium chloride, potassium chloride, sodium chlorite etc.) to swimming pools, spas, and other water features.
Pools, spas, and water features have a circulation system that continually pumps water from the pool or spa through a filter, heater, and sanitizer feed system before returning the water back to the pool, spa, or water feature. The circulation system is necessary to maintain the body of water at sanitary conditions. The water passes through the filter to reduce the accumulation of foreign material, such as hair, soil, or solids, in the pool or spa. Once the water has been filtered, the water passes through the heater, where the water is heated prior to returning to the pool, spa, or water feature.
In addition to filtering, pool, spa, and water feature water also requires regular sanitization in order to maintain hygienic conditions. Allowing sanitation levels to either fall below or rise above required specifications results in decreased efficiency of the system. Low levels of chemical sanitizer in the pool, spa, or water feature can contribute to algae blooms, bacterial breakouts, cloudiness in the water, and chemical imbalances. One method for sanitizing pool or spa water is by adding sodium chloride (NaCl) to the pool, spa, or water feature and passing the sodium chloride containing water through a chlorine generator where electrolysis converts the sodium chloride and water to sodium hypochlorite (NaOCl), by the following reaction:2NaCl(aq)+2H2O→Cl2(g)+H2(g)+2NaOH(aq)→NaOCl(aq)+H2O+NaCl(aq)+H2(g).
The chlorine generator is capable of being powered on and off depending on the concentration of sanitizer in the water. When there is a sufficient level of sanitizer in the pool or spa water, the chlorine generator is powered off and no reaction takes place as water passes through it. Thus, water circulating through the circulation system is filtered and heated, but the composition of the water is not altered. When the level of sanitizer has fallen to a minimum level, the chlorine generator is powered on and the sodium chloride and water passing through the chlorine generator is converted to sodium hypochlorite. The chlorine generator remains powered on until the concentration of sanitizer in the water has reached a desired steady state level.
To be effective, electrochemical generation of chlorine in a circulation system of a pool or spa requires sodium chloride to be maintained in the pool or spa water within a specified range to efficiently produce chlorine. Water in the pool or spa can be lost due to filter backwash, bather carry-out, and leaks in the infrastructure of the pool or spa body and plumbing. When the water level in the pool or spa decreases to a minimum level, fresh water must be pumped into the pool or spa to restore the water level to normal operating conditions. Fresh water is typically added to the pool or spa through a fresh water line plumbed directly to the pool or spa. As fresh water is added, sodium chloride must also be added to replenish loss of sanitizer from the pool or spa water.
Currently, sodium chloride is added directly to the pool or spa by manually pouring bags of granular salt along the perimeter of the pool and subsequently brushing the salt into the pool to increase the speed of dissolution and to inhibit corrosion of the plaster surface from direct contact with the sodium chloride. Although this method is necessary during the start-up process due to the high initial charge of salt required to reach target concentrations, this procedure becomes a time-consuming project when dosing for maintenance purposes. Manual addition of sodium chloride to a pool or spa also increases the risk of improperly dosing or adjusting the level of salt concentration in the pool. Increased voltage and heat generation of the system can also increase when the level of electrolyte is below the required specification, potentially resulting in electrical component failures. High levels of electrolyte in the pool can increase the potential for corrosion for pool equipment and pool surfaces.